Component with standoff and method of making same



United States Patent corporation of Germany No Drawing. Filed Dec. 17, 1963, Ser. No. 331,315 Dec. 18, 1962,

Claims priority, application Germany,

2 Claims. cl. 260-67) The present invention relates to a process for rendering high molecular weight compounds resistant to electrostatic charge.

High molecular weight substances have the disadvantage to accumulate electrostatic charge, particularly if they have good electrical properties. Owing to this electrostatic charging shaped articles made of, or containing, such substances have an increased tendency to attract dust. As a result thereof, the surfaces of such shaped articles exhibit, for example, the well known stains, crows feet and zigzag designs While fibers and fabrics become dirty within a short time. Beside a pronounced dirtying owing to electrostatic charge, a potential difference which under certain circumstances may be very high and which may give rise to sparking must be taken into consideration. Owing to these disadvantages arising from electrostatic charge the use of high molecular weight substances, for example plastics, may become unattractive for many fields of application.

Besides conditioning, two fundamental methods are known for preventing or reducing the electrostatic charge of high molecular weight compounds:

(1) Rendering shaped articles subsequently resistant to electrostatic charge by impregnation with solutions or dispersions of anti-static agents which are in many cases somewhat hygroscopic.

In this case, the surfaces of the shaped articles made of plastic materials are rendered conductive, that is the surface resistivity is strongly reduced so that electrostatic charge applied to the surface can flow off. The disadvantages of this method of rendering plastic materials resistant to electrostatic charge is obvious: when the conductive layer is damaged or wiped off the antistatic effect is lost, too.

(2) Incorporation of substances that prevent an electrostatic charge of shaped articles made of plastic materials.

This method offers considerable advantages over the above impregnation method. The antistatic effect is not only produced at the surface of the shaped articles and the antistatic layer cannot be wiped off, scratched off or detached mechanically. Attempts to incorporate in the plastic material the anti-static agents used for the impregnation method showed that the said compounds are generally ineffective when incorporated in the plastic material. In some cases this is due to the fact that they are partially or wholly decomposed at the sometimes rather elevated processing temperatures of the plastic materials. However, also compounds that are stable at these temperatures have no anti-static efficacy after incorporation. There is obviously a fundamental ditferen-ce between the reaction mechanism taking place in the method of rendering shaped articles resistant to electrostatic charge by the above incorporation and the reaction mechanism occurring in the impregnation process. This can also be proved by measurement. While the surface resistivity is strongly ice reduced by the impregnation with anti-static agents, the surface resistivity is substantially uneifected by the incorporation of anti-static agents even when the latter are very effective. In this case, the electrostatic charge cannot flow off at the surface of the articles, but instead the transmission resistivity is in most cases slightly modified. It has been found that also this method of measurement is not a measure of the resistance to electrostatic charge.

For rendering articles resistant to electrostatic charge by subsequent impregnation, various substances have been proposed. Exemplary of such substances are the following:

(1) nitrogen-containing compounds such as amines and quaternary ammonium salts,

(2) sulfonic acids and aryl-alkyl-sulfonates,

(3) phosphoric acids, aryl-alkyl-phosphates and phosphoric acid ester amides,

(4) polymers of polyhydric alcohols and the derivatives thereof.

As anti-static agents capable of being incorporated in the plastic material strongly hygroscopic inorganic salts have first been known. However, they are generally not used on account of the risk connected therewith of corrosion occurring on the processing machines.

More recently, further compounds have been proposed for incorporation to render high molecular weight organic compounds resistant to electrostatic charge.

It is known, for example, to add substituted phosphoric acid amides, urea derivatives and dithiocarbamates. Part of these compounds are, however, diificult to obtain or their purification requires considerable expenditure.

Now we have found that organic compounds of high molecular weight can be rendered resistant to electrostatic charge by incorporating into the organic compounds of high molecular weight a substituted carboxylic acid amine of the following formula R: wherein R represents H or CH R represents an alkyl radical having 2 to 26 carbon atoms, advantageously 12 to 26 carbon atoms, R represents a linear alkylene biradical having 1 to 5 carbon atoms, which may be substituted by an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radical, R represents H, an alkyl radical having 1 to 26 carbon atoms or a metal ion, and R R and R, may be substituted by a hydroxy group of an alkoxy group.

It has been found that the incorporation of small amounst of such substituted carboxylic acid amines already imparts excellent anti-static properties to organic compounds of high molecular weight so that articles made of such mixtures no longer charge electrostatically at the surface and no longer tend to attract dust.

The concentration of the substituted carboxylic acid amines in the plastic material is advantageously within the range of 0.1 to 7% by weight, advantageously 0.5 to 4% by weight.

It is advantageous to incorporate in the compounds of high molecular weight a mixture of 2 or more of the antistatic substances. In this case the anti-static efficacy may be enhanced by synergistic effects.

Exemplary of anti-static substances to be used in the process of the invention are the following:

Propionic acid ethyl ester-B-N-methyl-stearylamine Butyric acid stearyl ester-'y-N-methyl-dodecylamine Propionic acid methyl ester-fi-N-methyl-dodecylamine Propionic acid ethyl ester-fl-N-ethanolamine Valeric acid ethyl ester-fi-N-methyl-ethanolamine.

The mechanical and thermal properties, the thermostability under load as well as color and transparency of 3 the polymers are practically unaltered by the addition of the said substances. The working conditions and the temperature range in which the plastic material can be shaped by a thermoplastic process remain the same. Care has tion or by application to the pulverulent or granular high molecular polymer. The admixture is most advantageously effected prior to or during the processing. It was found that the technique of incorporation is of little imonly to be taken that such anti-static substances are chosen 5 portance. It is important, however, that the anti-static as are stable at the temperature at which a plastic maagents are distributed in the plastic material as uniformly erial used in a given case is processed. as possible.

The products are well compatible with all polymers. The high molecular weight compounds rendered re- The anti-static eifect that can be obtained is independent sistant to electrostatic charge by the process of the inof the moisture of the sourroundings and practically of vention can be processed by all customary processing an unlimited duration. Exudation was not observed. Moremethods, for example, on molding presses, injection moldover, the surface does not become hygroscopic but reing machines or extruders. From these high molecular mains unchanged. By the addition of the substances of weight polymers, therefore, there can be made compresthe general formula described above all high molecular sionand injection molded articles, semi-finished goods, weight materials can be improved that have the tendency sheets, inflated hollow articles, tubes, fibers, filaments and of getting dirty by attracting dust owing to electrostatic monofilaments. The resins admixed with the compounds charging. These compounds exhibit a particularly good mentioned above can be processed in the usual manner efiicacy, for example, in polystyrene and in copolymers as resin varnish or casting resin or in combination with of styrene with monomers that are copolymerizable with glass fibers and/or fillers. The high molecular weight styrene such, for example, as butadiene, acrylonitrile polymers which have been rendered resistant to electroand/or vinyl carbazole, in polyvinyl chloride and vinyl static charge in this manner are particularly interesting chloride copolymers, polyterephthalates, polyolefins obfor packaging purposes (packing material, canisters, bottained by the high pressure process or the low pressure tles, breakers), as accessories for vacuum cleaners, bandprocess (Phillips process or Ziegler process) such, for conveyors, showroom patterns and masters, parts of casexample, as the polymers and copolymers of ethylene, ings (for example for radio and television sets, vacuum propylene, butene-( 1), pentene-(l), 4-methyl-pentenecleaners), electric installations such a lighting fixtures, (1), hexene-(l), 5,5-dimethyl-hexene-(l), octadecenecable insulations, plugs, switches or armatures, air con- (l), 4-phenyl-butene-(l) as Well as vinylcyclohexene, ditioning and ventilating equipments, plastics table ware, polycarbonates, polyoxymethylenes, polyacrylonitrile, kitchen machinery, filaments, fibers, fabrics, sheets, lacpolyacrylic acid esters, polymethacrylic acid esters, poly- 3 quers, that is in all those cases in which resistance to acetates, polyvinyl acetates, polyamides, polyurethanes, electrostatic charge is required. cellulose derivatives and mixtures containing the enumer- The anti-static effect of inorganic or organic comated polymers. Also unsaturated polyesters and epoxy pounds in high molecular weight materials can be de resins hardened with reagents having a basic character as termined most easily by means of cigarette ash. For test- Well as raw materials for lacquers can Without difficulty be ing these materials plates obtained by extrusion, injectionrendered resistant to electrostatic charge prior to or duror compression molding are vigorously rubbed with a ing their processing by an addition of the above menwoolen cloth for about 15 seconds and held about 2 mm. tioned anti-static agents. above a layer of cigarette ash. When the plates have good The high molecular weight compounds may further anti-static propert es, they do not attract cigarette ash. contain usual additives, for example stabilizers, fillers and Since cigarette ash is somewhat hygroscopic and moist dyestuffs. cigarette ash has different electrical properties, the ash The substances to be incorporated in accordance with us f r th t st s ould be not older than 6 hours. the invention may be added prior to or during the poly- The table given below which lists the test results shows merization and also subsequently to the pulverulent high that an excellent anti-static effect can be attained with all molecular weight polymer as well as to the granular 0f the P S e merated. product. Depending on the nature of the plastic material The following examples serve to illustrate the inventhe said compounds may be admixed in the melt, in solution but they are not intended to limit it thereto.

TABLE Ash test. Ex. Plastic Material Anti-static agent Formula iil 132331 NO- percent days, respectively CHa O i Low pressure polyethylene. Propionio acid ethyl ester-B-N-methyl- N-CHz-CI-Iz--OCzHs 2 i stearylamine.

CH: O 2 Polypropylene Butyric scid-stearylester-,N-methyl- NcH -cH,-(3H,- i-0c rr 1,5 1

dodecylamine.

Cn n

CH: 3 Polystyrene {Propionie acid methylester-a-N-meth- 1, 5 (l) 4..-... Polyamide yl-dodeeylamine. N(JH UH --(J-0 CH 1,0 (l) CuHu H 5 Polyester resin hardened Propiionieacidethylester-B-N-ethnnol- N-CHg-CHz-CL-OCnH: 1.0 (I) am [10. HOCIH CH| 6 Polycarbonate Valerie acid ethyl ester-a-N-methyl- N-(cHm-ib-o (1,11, 1 (I) ethanolamiue. H O C H! 1 No attraction of ash.

wherein R is a member selected from the group consisting of H and CH R means alkyl with 2 to 26 carbon atoms,

R, means a linear alkylene biradical having 1 to 5 carbon atoms, Which may be substituted by a member selected from the group consisting of alkyl, cycloalkyl, aryl, alkylaryl and arylalkyl,

R is alkyl having 1 to 26 carbon atoms, and R R and R may be substituted by a member selected from the group consisting of hydroxy groups and alkoxy groups.

2. The composition of claim 1, wherein the polymeric material is selected from the group consisting of polystyrene, copolymers of styrene and copolymerizable monomers, homoand copolymers of vinyl chloride, polyterephthalates, polyolefins, polycarbonates, polyoxymethylenes, polyacrylonitrile, polyacrylates, polymetharcylates, polyacetates, polyvinylacetals, polyamides, polyurethanes, epoxide resins and cellulose polymers.

References Cited UNITED STATES PATENTS 2,953,526 9/1960 Bergman et al. 2528.8

WILLIAM H. SHORT, Primary Examiner.

SAMUEL H. BLECH, Examiner.

R. LYON, Assistant Examiner. 

1. COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF (A) AN ORGANIC POLYMERIC MATERIAL OF HIGH MOLECULAR WEIGHT AND (B) FROM 0.5 TO 4% BY WEIGHT BASED ON (A) AT LEAST ONE SUBSTITUTED CARBOXYLIC ACID AMINE OF THE FORMULA 